Complete and universal implant for front path hernia repair

ABSTRACT

The invention concerns an implant comprising: a planar part made of biocompatible material, knitted with monofilament or multifilament yarns with an armour providing it with run-resistant and macroporous properties; and a hollow protrusion made of biocompatible material, projecting from a surface of said planar part, said protrusion having a longitudinal axis perpendicular to the plane of the planar part, an orifice located in said plan and a flat base parallel to the planar part. The invention is characterized in that the protrusion is shaped like a cylindrical cup, and the base of said protrusion is spaced apart from said opening by a distance whereof the value is not more than the value of the diameter of the protrusion.

The present invention concerns an implant for treatment of hernias, inparticular inguinal, femoral or crural hernias, by an anterior approach.It also concerns a method for production of this implant.

It is known to treat an inguinal, femoral or crural hernia by using, incombination, a flat implant in the form of a sheet, commonly referred toas a patch, and a three-dimensional implant forming an obturator andcommonly referred to as a plug. The patch permits reinforcement of theposterior wall of the inguinal canal and helps avoid the risk ofrecurrence. The plug is introduced deep into the defect which is left bythe reduction of the hernia and which it is able to close off.

It is also known, from document WO 97/35533, to form an implantcomprising two layers made of different materials, one of which promotesadhesion of the tissues, and the other of which prevents such adhesion.By suitable folding of the implant, it is possible to exploit therespective properties of these layers. According to one embodimentdescribed by said document, the implant comprises an expandableprotuberance of frustoconical shape formed in the adhering layer.

This flexible and frustoconical protuberance does not seem able to adaptperfectly to the defect left by the reduction of the hernia, nor does itseem able to completely withstand the pressure exerted on it by thehernial sac once the implant is in place. The result of this is a notinconsiderable risk of recurrence, especially in the case of eversion ofthe protuberance under said pressure.

Admittedly, said document discloses the possibility of filling thecavity delimited by this protuberance and by the non-adhering layer,using an inert gas or another suitable inert material, and this seemsable to provide the protuberance with a certain degree of rigidity.

However, this filling technique is considered to involve a number ofserious operational drawbacks and is overall regarded as undesirable.Moreover, the resulting stiffening of the protuberance is temporaryanyway, since the prior art document indicates that this protuberance,when it has been thus filled, can compress over the course of time as aresult of the contraction of the tissues surrounding the hernial defect.

The object of the invention is to remedy all of these disadvantages.

The implant according to the invention comprises, in a manner known perse:

-   -   a flat part made of biocompatible material, knitted from        monofilaments or multifilaments, with a structure which prevents        unraveling and provides macroporosity, and    -   a hollow protuberance made of biocompatible material protruding        from one face of this flat part, this protuberance having a        longitudinal axis perpendicular to the plane of the flat part,        an opening situated in this plane, and a flat base parallel to        the flat part.

According to the invention, the protuberance is in the form of acylindrical cell, and the base of this protuberance is spaced apart fromsaid opening by a distance (h) whose value is not greater than the valueof the diameter (d) of the protuberance.

The implant according to the invention thus specifically comprises aprotuberance of cylindrical shape and with a height smaller than itsdiameter. This protuberance consequently has a peripheral wallperpendicular to said base and has a relatively limited height.

This shape gives the protuberance relative inherent rigidity, allowingit to completely withstand the pressure which the hernial sac exertsagainst said base once the implant is in place. Effective prevention ofthe risk of eversion is thus achieved.

This same shape allows the protuberance to adapt relatively precisely tothe shape of the hernial defect, so that said peripheral wall comes intocontact with the surrounding tissues which support this wall and thuscontribute to the rigidity of the protuberance.

After it has been put in place, the protuberance can be fixed to thesesurrounding tissues by means of one or more sutures; the flat part canalso be fixed to the surrounding tissues, in particular to the inguinalligaments or to the inguinal floor, by one or more sutures.

The protuberance is preferably formed substantially at the middle of thewidth of the flat part and approximately one third of the way along thelength of said flat part.

The flat part can thus be cut out as a function of the size of thedissection performed, so as to perfectly match the posterior wall of theinguinal canal. This cut is made without fraying and with emission of aminimum quantity of particles, by virtue of the non-unraveling structureconstituting the knit.

In one embodiment of the invention, the protuberance has a diameter ofthe order of 20 millimeters and a height not greater than that diameter.

The flat part can be rectangular with straight or rounded corners. Itcan have a width of the order of 60 millimeters and a length of theorder of 120 millimeters.

By virtue of its configuration and its dimensions, this implant issuitable for all types of hernial repairs, whether indirect, direct orcrural.

In one embodiment, the face of the flat part intended to come intocontact with the posterior anatomical structures has a roughnessresulting from the texture and/or the structure of the knit from whichthis flat part is composed.

The protuberance can be formed independently of the flat part. The flatpart then comprises a cutout formed in it in the zone of implantation ofthe protuberance, and the protuberance comprises a circular base joinedby any means, such as welding, adhesive bonding or sewing, to thecircular edge delimiting the cutout made in the flat part.

The flat part and the protuberance can then be made of knits which aredifferent in terms of their texture and/or structure and which providethe properties sought for this flat part and for this protuberance, inparticular a roughness or softness, and semi-rigidity or flexibility,respectively.

The flat part and/or the protuberance can be impregnated with substanceswhich are bactericidal and/or anti-inflammatory and/or analgesic.

The flat part can also have, locally, a slit for the passage of thespermatic cord. The invention also relates to a method for obtaining theimplant described above.

The method comprises the steps of:

-   -   a) producing a knit of thermoformable biocompatible material,        consisting of monofilaments or multifilaments, and    -   b) stamping the knit so as to obtain the shape of the        protuberance to be formed, and heating this knit, it being        possible for this stamping operation and this heating to be done        simultaneously or in succession.

The knit produced in step a) advantageously has dimensions such that,after shaping of the protuberance, it is also able to form said flatpart, either as it stands or after appropriate cutting.

If not, the method comprises the steps of:

-   -   making a cut in a knit portion which, either as it stands or        after appropriate cutting, is able to form said flat part, and    -   joining the protuberance by any means such as welding, adhesive        bonding or sewing to the circular edge delimiting the cutout        formed in the flat part.

The method can comprise, between steps a) and b) cited above, the stepsof:

-   -   placing the knit between two plates made of heat-conducting        material, the first of which plates comprises a hole with a        diameter greater than the external diameter of the protuberance        to be formed, and the second of which plates comprises a plug        with a diameter slightly smaller than the internal diameter of        the protuberance to be formed;    -   bringing these two plates together so that the plug of the        second plate is engaged in the hole of the first plate, thereby        effecting said stamping operation, and    -   keeping these plates in this position and heating them for the        period of time necessary to form the protuberance.

Alternately, said second plate can comprise, instead of said plug, ahole with a diameter at least equal to the internal diameter of theprotuberance to be formed, and a heating mandrel is engaged through theholes in the two plates so as to form the protuberance.

When the protuberance is made from a knit permitting formation of theflat part, the movement of the two plates toward each other ispreferably such that the knit can slide between the plates duringformation of the protuberance by means of said plug or said heatingmandrel.

This sliding makes it possible to retain a substantial density ofmaterial remaining in the area of the protuberance.

The invention will be clearly understood from the following descriptionof two embodiments of the implant, this description being made withreference to the attached diagrammatic drawing. In this drawing:

FIGS. 1 and 2 are views in perspective and in longitudinal section,respectively, of the implant according to a first embodiment;

FIG. 3 is a longitudinal section through this implant when it is inplace in a hernial defect;

FIGS. 4, 5 and 6 are partial views of this implant, showing theconditions of placement of the implant for the repair of, respectively,a left indirect hernia, a left direct hernia, and a right crural hernia;

FIGS. 7 and 8 are views of the implant according to the secondembodiment of the invention, FIG. 7 being a perspective view prior toassembly of its constituent elements, and FIG. 8 being a longitudinalsection in the assembled state.

In the embodiment shown in FIGS. 1 and 2, the implant is composed of aflat part 2, of general rectangular shape, with straight or roundedcorners. Protruding from one of the faces of this flat part 2 there is aprotuberance 3 in the shape of a cylindrical cell whose longitudinalaxis is perpendicular to the flat part 2. The opening 3 a of the cellformed by the protuberance is situated in the plane of the flat part 2,and the base 3 b of this protuberance 3, opposite the opening 3 a, isflat and parallel to said flat part 2.

The flat part 2 and the protuberance 3 are in one piece and made from aknit of monofilaments or multifilaments of polypropylene or polyethylenehaving a diameter of between 0.10 and 0.20 millimeter.

According to a preferred embodiment of the invention, the implant ismade from a knit of 0.15-mm polypropylene monofilaments, with openmeshes, this knit being formed of two knitted sheets in accordance withthe following respective configurations: sheet 1: 32/01/12/43; sheet 2:32/01/12/43.

These structures form non-unraveling meshes which give the knitsemi-rigidity, but with a possibility of deformation.

The cylindrical protuberance 3 is obtained by thermoforming of thisknit.

According to one possible embodiment, the flat part 2 is compressedbetween two metal plates, of identical dimensions, one of whichcomprises a plug having the internal dimensions of the protuberance tobe formed, and the other of which comprises an opening having theexternal diameter of the protuberance to be formed. The two plates areheated to a temperature of the order of 140° C. for about 25 seconds.The heat and the mechanical stress of engagement of the plug in theopening of the other plate, combined with the possibility of deformationof the knit constituting the flat part, form a protuberance in thelatter, which protuberance at the end of production has relativerigidity and a cylindrical wall with an axis substantially perpendicularto the plane of the flat part.

The component thus formed is then subjected to cooling with air for aperiod of the order of 15 seconds.

The knit is not gripped tightly during the stamping operation and istherefore able to slide between the plates during production of theprotuberance. This sliding makes it possible to retain a substantialdensity of material remaining in the area of the protuberance.

After the stamping operation, the component formed has the followingcharacteristics:

-   -   density of the knit:        -   in the area of the flat part: approximately 84 g/m²        -   in the area of the base 3 b: approximately 72 g/m²        -   in the area of the peripheral wall of the protuberance 3:            approximately 80 g/m²    -   rupture strength of the knit in the area of the flat part:        -   longitudinal direction: 490 N        -   transverse direction: 318 N    -   tear strength of the knit in the area of the flat part:        -   longitudinal direction: 24 N        -   transverse direction: 69 N    -   resistance to compression of the protuberance:        -   1.7 N for a protuberance of approximately 25 mm in diameter            and 18 mm in height        -   2.6 N for a protuberance of approximately 25 mm in diameter            and 14 mm in height.

According to another possible embodiment, the knit is placed between twometal plates heated to an adjustable temperature and comprising, facingone another, two cylindrical bores through which a heating mandrel canbe engaged.

In a preferred embodiment, the flat part 2 is rectangular and has awidth l of the order of 60 millimeters for a length L of the order of120 millimeters, while the protuberance 3 has a diameter d of the orderof 20 millimeters for a height h which is not greater than 20millimeters and is, for example, 15 millimeters.

The protuberance 3 is formed so as to be substantially at the middle ofthe width of the flat part 2 and one third of the way along its lengthrelative to one of its ends, as is shown by the distance S in FIG. 1.

The lower face 2 a of the flat part 2, that is to say the face fromwhich the protuberance 3 protrudes, can be rough so as to increase itsability to attach and adhere to the posterior anatomical structures.This roughness results from the texture and/or the structure used.

In the embodiment shown in FIGS. 7 and 8, the flat part 22 and theprotuberance 23 are produced separately. The flat part 22, ofrectangular shape with rounded ends 22 a, comprises a circular cutout 24in the zone of implantation of the protuberance 23. The protuberance 23is cut, after its formation by thermoforming, from another knit in orderto present the cylindrical shape shown in FIG. 7 with, near its opening23 a, a circular base 23 c, straight or with a flange. After engagementof the cell 23 into the cutout 24, it is joined to the flat part 22,depending on the nature of the materials from which these two elementsare made, by welding, bonding or sewing the circular base 23 c of theprotuberance 23 to the circular edge 24 a of the cutout 24, as isillustrated by the broken line 25 in FIG. 8.

The flat part 22 and the protuberance 23 can thus be formed from knitswhich differ in their texture and/or their structure so as to give,respectively, a roughness or softness, and semi-rigidity or flexibility.Thus, for example, the flat part 22 is made of multifilaments ofpolyethylene or polyester, giving it softness on contact, with astructure which does not unravel but confers flexibility and forms burrsfavoring adherence, while the knit in which the protuberance 23 isformed is made of monofilaments of polypropylene with a structureconferring greater deformability and semi-rigidity after thermosetting.

The implant, irrespective of the way it is formed, is intended to permithernial repair by an open anterior approach. When it is put in place,and as is shown in FIG. 3, the protuberance 3 has dimensions allowing itto adapt to all the hernial openings 4 formed in the muscles 5juxtaposed to the transverse fascia 6 and to the peritoneum 7. Theconnection of the protuberance 3 to the edges 4 a of the muscle opening4 is effected by sutures 8.

The flat part 2, which extends around the opening 4 against the inguinalwall, strengthens the latter, thus avoiding recurrences. This flat part2 is fixed by a few suture points 9.

When the implant is thus in place, the protuberance 3 fits perfectlyinto the muscle opening 4 without generating any reaction indicative ofthe presence of a foreign body. Its top is flat and atraumatic, as itdoes not extend beyond the thickness of the wall, and limits the risksof deep visceral lesions caused by erosion. Moreover, by virtue of therigidity of its constituent material and of its formation bythermoforming, there is no risk of the protuberance 3 deforming orundergoing eversion.

FIG. 4 shows the placement of an implant according to the invention fora left indirect hernia. To facilitate engagement of the protuberance 3in the inguinal ring 12 and to permit passage of the spermatic cord 10,the surgeon adapts the implant by forming a slit 13 in it in order toallow this cord 10 to pass through. In the drawing, reference number 14designates the external oblique muscles, and reference numbers 8 and 9designate the suture threads described with reference to FIG. 3.

The surgeon can adapt the outer shape of the flat part 2 to the size ofthe dissection, in order to perfectly match the latter.

FIG. 5 shows the placement of an implant according to the invention inthe context of repairing a left direct hernia. This involves repairingan orifice 15 formed in Hesselbach's triangle, in a zone more remotefrom the inguinal ring 12. For this repair, the implant is turnedthrough 180° relative to the position it occupies in FIG. 3, so that,after the protuberance 3 has been placed in the orifice 15, the largerportion of the flat part 2 extends in the direction of the inguinal ring12. To permit the passage of the spermatic cord 10, the surgeon forms anopening 16 with a slit 17 in the flat part 2 and, if appropriate, adaptsthe outer shape of the flat part 2 to the shape of the dissection.

FIG. 6 shows the treatment of a right crural hernia, which necessitatesclosure of the femoral ring 18, arranged in proximity to the inguinalligament 19, by means of the protuberance 3. In this case, the surgeonadapts the implant by cutting it to length so as to give itsubstantially the same length on either side of the protuberance 3.

It will be evident from the above that the implant according to theinvention is universal because it can be applied in the repair ofindirect hernias, direct hernias and crural hernias, and that, in allthese applications, it ensures not only the closure of the hernialorifice but also the strengthening of the inguinal floor around thisorifice, thereby reducing the risks of recurrence, but without forming abody whose tightness would be a source of problems for the patient.

1. A complete and universal implant for the repair of hernias by ananterior approach, composed of a sheet of biocompatible material, madeof monofilaments or multifilaments, knitted with a structure whichprevents unraveling and provides macroporosity, and of a hollowprotuberance made of biocompatible material protruding from one face ofthis sheet with which it forms a one-piece assembly; the sheet is flatand extends over a surface allowing it to cover the posterior wall ofthe inguinal canal, and the protuberance is situated at the middle ofthe width of the sheet and approximately one third of the way along itslength, said protuberance having a longitudinal axis perpendicular tothe sheet, forming an opening situated in the plane of the sheet, andhaving a base which lies opposite the opening and is flat and parallelto the sheet; said implant being characterized in that the protuberanceis in the form of a cylindrical cell, and in that its base, lyingopposite said opening, is spaced apart from the latter by a distancewhose value is not greater than the value of the diameter of the cell.2. The implant as claimed in claim 1, characterized in that theprotuberance in the form of a cell has a diameter whose value is of theorder of 20 millimeters and a height whose value is not greater thanthat dimension.
 3. The implant as claimed in claim 1, characterized inthat the flat sheet, of overall rectangular shape with straight orrounded ends, has a width of the order of 60 millimeters and a length ofthe order of 120 millimeters, so as to form, around the protuberance,forming an obturator after its introduction into the opening of a wall,a flat implant which strengthens said wall and is able to be connectedto it by sutures arranged away from the opening.
 4. The implant asclaimed in claim 1, characterized in that the face of the sheet intendedto come into contact with the posterior anatomical structures has aroughness resulting from the texture and/or the structure of the knitfrom which this sheet is composed.
 5. The implant as claimed in claim 1,characterized in that the protuberance in the shape of a cell isproduced by thermal deformation of the sheet whose texture and/orstructure give it semi-rigidity.
 6. The implant as claimed in claim 1,characterized in that the protuberance in the shape of a cell isproduced independently of the sheet and its circular base is connectedby welding, adhesive bonding or sewing to the circular edge of a cutoutformed in the sheet in the zone of implantation of this protuberance. 7.The implant as claimed in claim 6, characterized in that the sheet andthe protuberance are made from knits which are different in terms oftheir texture and/or structure and which provide, respectively, aroughness or softness, and semi-rigidity or flexibility.
 8. The implantas claimed in claim 1, characterized in that its sheet and itsprotuberance are impregnated by substances which are bactericidal andanti-inflammatory or analgesic.
 9. The implant as claimed in claim 1,characterized in that its sheet has, locally, a slit for the passage ofthe spermatic cord.
 10. A method for obtaining the implant as claimed inclaim 1, characterized in that it comprises the steps of: compressingthe flat sheet between two metal plates, of identical dimensions, one ofwhich comprises a plug having the internal dimensions of theprotuberance to be formed, and the other of which comprises an openinghaving the external diameter of the protuberance; heating the twoplates; engaging said plug in the opening of the other plate in such away as to form, in the sheet, a rigid protuberance with a substantiallycylindrical wall which is substantially at right angles to the flatsurface of the sheet.
 11. A method for obtaining the implant as claimedin claim 1, characterized in that it comprises the steps of: placing theflat sheet between two metal plates which comprise, facing one another,two cylindrical bores through each of which a heating plug can bepassed; heating this plug; engaging said plug in the opening of theother plate in such a way as to form, in the sheet, a rigid protuberancewith a substantially cylindrical wall which is substantially at rightangles to the flat surface of the sheet.